Question

For example, a query can return ‘yes’ or ‘no’. How can I make it return 1 if it’s a yes and 0 if it’s a no?

Answer 1

If you only want a yes if it is 1, and every other value results in a no, you can do this:

select case 
        when MyColumn = 'yes' then 1 
        else 0 
    end as MyDerivedValue
from MyTable

Or, you can be more specific:

select case MyColumn 
        when 'yes' then 1 
        when 'no' then 0
        when 'maybe' then 2
        else -1
    end as MyDerivedValue
from MyTable